The preheating effect of dry okara on the specific loaf volume of bread containing okara was investigated. The water absorbance of okara was decreased by heat treatment. A higher heat treatment extracted a lower amount of protein from the okara. The protein with a larger molecular weight decreased at the higher temperatures. This might be caused by the denaturation/coagulation of the protein and by the decrease in solubility of the protein due to an amino-carbonyl reaction. The specific loaf volume of the okara bread increased by increasing the temperature of the okara. However, the specific loaf volumes of bread containing okara heated at 100°C and that of unheated okara were very similar. On the other hand, the hardness decreased and the cohesiveness increased by increasing the heating temperature of the okara. It was suggested that the preheating of dry okara produced a higher specific volume of the okara bread.